Portable communication devices (e.g., smart phones and smart watches) are becoming increasingly equipped with environmental sensors such pressure, temperature and humidity sensors, gas sensors and particulate matter (PM) sensors. For example, a pressure sensor can enable health and fitness features in a smart watch or a smart phone. A measured pressure can then be converted (e.g., by a processor) to other parameters related to pressure, for example, elevation, motion, flow or other parameters. Pressure sensors can be used to measure pressure in a gas or liquid environment.
Pressure sensors can vary drastically in technology, design, performance and application. In terms of employed technologies, pressure sensors can be categorized as, for example, piezoelectric, capacitive, electromagnetic, optical or potentiometric pressure sensors. The micro-electro-mechanical system (MEMS) type pressure sensors used in smart phones or smart watches are generally capacitive-type pressure sensors. Pressure sensors using interim gel have been widely used in the microelectronic devices, but the gel can be susceptible to environmental contaminations and water occlusion. There is a need for pressure sensors that can detect presence of a water droplet on the gel.